Question

What is Hormogonia?

Answer 1

Hint: Cyanobacteria are aquatic and photosynthetic, that means they live in water and they can produce their own food. As they are a form of bacteria, they are microscopic and unicellular as well. Only a single cell performs all the necessary functions. From cyanobacteria, the origin of plants occurred.

Complete answer:
Cyanobacteria are unicellular, autotrophic, aquatic organisms. They are a form of bacteria which is microscopic and unicellular.
Hormogonia is a portion of filament of cyanobacteria which detaches to form a reproductive body. They are motile filaments of cells in the order of Nostocales and Stignomatales. They are formed in vegetative reproduction in unicellular, filamentous cyanobacteria.
When cyanobacteria is exposed to environmental stress or in new media, it differentiates into hormogonia.
Differentiation of hormogonium is crucial for the development of nitrogen-fixing plant cyanobacteria symbiosis, particularly in the genus Nostoc and their hosts. When plant hosts secrete hormogonium inducing factor (HIF), in response to this cyanobacterial symbionts start differentiating into hormogonia and then into vegetative cells. This whole process takes somewhere around 96 hours. They manage to reach the plant host by this time. Bacteria then differentiate into specialized nitrogen-fixing cells called heterocyst and enter into working symbiosis with the plant.
Hormogonia can be upto hundreds of micrometers in length depending upon species and can travel upto 11 micrometer per second.

Note:
Cyanobacterias are a form of bacteria which are unicellular, autotrophic, microscopic, aquatic organisms. Portion of filament of cyanobacteria which detaches itself to form the reproductive body is known as hormogonia.